Tom Chivers is the Telegraph's assistant comment editor. He writes mainly on science. Not a poet - that's the other Tom Chivers. Read older posts by Tom here.

Don’t play politics with votes for 16-year-olds

From Tuesday's paper: Party self-interest shouldn’t be allowed to colour the debate about widening the franchise

It’s a sad thing that, when politicians move to extend the franchise or otherwise change the voting system, the party doing it always seems to be the one that benefits.

So, for instance, David Cameron and the Conservatives are keen to reform the constituency boundaries – something that needs doing to ensure that the constituencies each have roughly the same number of voters, but which, it is noticeable, will be of considerable benefit to the Conservatives. Equally predictably, Labour are against it, and the Lib Dems will join whichever side they happen to be less annoyed with at any given moment.

Similarly, the Lib Dems were vocal in their support of the alternative vote system, a semi-skimmed version of proportional representation which just happened to be favourable to their party. It would not surprise me to learn that in the 19th century the Liberal Party decided to back women’s suffrage on the basis of favourable polling data.

The fact that it’s self-interested doesn’t mean it’s wrong; perhaps it’s perfectly right to give younger teenagers the vote. The question we need to answer first is this: are children of that age ready to make informed and responsible decisions? And second, are we unfairly denying them involvement in democracy?

We certainly don’t entirely trust young people with important decisions. We don’t allow younger teenagers to drink, or under-17s to drive. We do allow them to have sex, but not to go to the cinema to watch other people pretend to have sex in films. We just about let them go and fight for their country; they can join the Army from the age of 16, but they’re not allowed to take part in operations until they’re 18. We don’t let them buy cigarettes.

A part of the brain which is tied up with emotional responses, the amygdala, is fully active in teenagers; by contrast, the frontal cortex, which is involved in impulse control and reasoned behaviour, is very much still under construction until well into adulthood. Adolescent brains have far more grey matter than adult ones: it is believed that the process of pruning the grey matter, which continues until the early twenties at least, makes the brain work more efficiently, and is involved in adult behaviour like forward planning.

The upshot of this is that adolescents are more likely to act impulsively, more likely to get into fights and accidents or engage in dangerous behaviour, and less likely to think about the consequences of their actions. Between the ages of 15 and 19, your likelihood of dying in an accident is six times as high as between 10 and 14; crime rates spike at this age, as well as incidences of binge drinking and drug use.

It’s tempting to suggest that this impulsiveness is a factor in the independence question. The decision to leave the UK is a complex and difficult one, with costs and benefits to factor in, but the Yes answer is easy to paint in simple, intuitive terms (freedom, independence, liberty) while the No case involves much more complex (though not necessarily more worthy) arguments – economic stability, shared history, mutual defence – which may be harder to grasp instinctively and thus would be less appealing to an impulsive adolescent mind. Of course, this is pure speculation, but it's a plausible story.

But perhaps it doesn’t matter whether adolescents are, on average, less capable of making reasoned decisions than adults. There are lots of adults who similarly lack impulse control, but we would never consider disenfranchising them; we accept that everyone has a right to a stake in the electoral process.

You might argue that teenagers deserve to vote simply because they, too, are taxed, and suffer the consequences of political decisions, just as we ancients do: more so, in fact, since they’ll generally live longer with them. The reverse argument, of course, is that these same teenagers will be able to vote in two years’ time, and 16 years is just as arbitrary a cut-off line as 18.

There’s a serious discussion to be had, here, and a serious case that should be made – preferably by powerful young voices, a group of generational Suffragettes. What it shouldn’t be is an opportunistic land-grab by a self-interested political party. Perhaps 16-year-olds should vote, but it should be something we look at in its own right, not a piece of age-related gerrymandering by Alex Salmond.